While I will not get into an argument over the merits of the blue LED vs red or any other colour,
here are some points why the creation of the blue LED and hence white lighting is revolutionary according to Professor Emeritus Christopher Hall, Centre for Materials Science and Engineering, University of Edinbugh:

The fact that it is blue didn't mean the technology from 1972 was a commercially viable option - especially for high brightness (efficiency), high power, blue. In fact, it wasn't. Not even close to a solution that would impact downstream applications. The multiple layers of modern LEDs were really a recent discovery made possible by the availability of high purity trimethyl gallium (6N and better) and high purity ammonia (7N and better).

The fact that it is blue didn't mean the technology from 1972 was a commercially viable option - especially for high brightness (efficiency), high power, blue. In fact, it wasn't. Not even close to a solution that would impact downstream applications. The multiple layers of modern LEDs were really a recent discovery made possible by the availability of high purity trimethyl gallium (6N and better) and high purity ammonia (7N and better).

The general consensus today seems to be that efficiency improvements that make products economically manufacturable are the most valuable contribution to our society. But I can’t help but be concerned about the gradual decline in fundamental research-and-development spending in the US in the physical sciences.

Where will the inventions come from in the future that will lend themselves to optimization, like the blue LED? Invention of the Mg-doped GaN light emitting diode was a great achievement by Herbert Maruska, as were the efficiency improvements by the Nobel Prize winners. I hope we can continue to grow both types of contributors in the future.

I have no idea how the 1973 invention related to the winners' discoveries other than the emitted color.

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The basic GaN process as detailed in the patent with magnesium doping is the basis for almost all blue LEDS including the 'efficient' ones. I don't have a problem with the winners of the prize, they do deserve it if those are the rules of the prize but IMO "invention of efficient" is 90% good engineering not physics after the basic principles are discovered.

For this year, one of the developers, Shuji Nakamura, was noted for developing an efficient form of the Mg-doped GaN that lent itself to cost effective manufacturing. Akasaki, Amano, and Nakamura chose to base their work on Maruska’s discovery that doping GaN with magnesium would produce blue light. Maruska did this 20 years before development of the “efficient” improvements covered in the Nobel Prize.

The basic GaN process as detailed in the patent with magnesium doping is the basis for almost all blue LEDS including the 'efficient' ones. I don't have a problem with the winners of the prize, they do deserve it if those are the rules of the prize but IMO "invention of efficient" is 90% good engineering not physics after the basic principles are discovered.

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Magnesium is indeed old technology. Apparently why it is not the key dopant for the Nobel winner - it is used to make the pGaN layer. The recent LED technology uses a GaN/InN alloy as tuned band gap material as a MQW layer (micro-quantum well). It is possible to have several MQW layers. GaN/InN alloy band gaps from 0.7 (IR) to 3.4 eV (UV) can be tuned with only Trimethylgallium, trimethyl indium and ammonia in a CVD tool.

Maybe this achievement would have been better for the chemistry category rather than physics.

Trimethylindium, one of four high purity organometallics needed for the GaN LEDs, has only been available commercially for the past 12 years or so.

The only indium mention in the original patent is in the solder for the wire bonding.